1. Field of the Invention
The present invention relates to an angle measuring system having a coupling for the torsion-proof connection of a base with a stator, wherein the coupling permits radial and axial compensating movements of the stator with respect to the base.
2. Discussion of Related Art
Angle measuring systems are employed, for example, for measuring the angular position of an engine shaft. For this purpose, the angle measuring system has a rotating element (rotor) and a static element (stator) in its housing. The rotor is fastened on the engine shaft, so that it follows all movements of the shaft and rotates along with the shaft in relation to the stator. The rotor has a graduation, which is scanned by a scanning unit of the angle measuring system fastened to the stator, and whose signals are employed for calculating the angle position of the shaft.
In this case the scanning unit, and therefore the stator, must be seated in such a way that they are connected with the motor housing in a torsion-proof manner with respect to the rotor. Each rotating movement of the stator would lead to an error in the measurement of the angular position. But the stator should be able to follow axial and radial movements of the shaft. In this way it is assured that the distance between the rotating graduation and the scanning unit does not change and a constant signal quality is obtained. This is achieved in that an appropriate coupling is provided between the stator and the base of the angle measuring system, which is fixedly connected with the motor housing. The base can be a portion of the housing of the angle measuring system here.
An angle measuring system with such a coupling is described in DE 299 11 508 U1, for example. In the course of the use of such angle measuring systems, tolerances are predetermined for the maximum deflection of the motor shaft in the radial and axial direction. If these are exceeded, there is the danger of the destruction of the coupling, since it is made of a flexible, shaped sheet metal element.
An angle measuring system with a coupling of flexible sheet metal elements is also described in Japanese Laid-Open Utility Model 62-156822. There it is provided to limit the axial movements permitted by the coupling by means of a stop. However, the coupling used only permits axial movements, which are limited by the stop, which is constructed from additional components and is therefore expensive.
It is therefore an object of the present invention to recite an angle measuring system, which limits the radial and axial movements of the stator by simply constructed stops and in this way prevents damage to the coupling between the stator and the base.
This object is attained by an angle measuring system that includes a rotor that rotates about an axis of rotation. A scanning unit is spaced from the rotor and the scanning unit is attached to a stator. The angle measuring system further includes a base and a coupling connected to the base and the stator so that a torsion-proof connection between the base and the stator results, wherein the coupling permits radial and axial compensating movements of the stator with respect to the base and the axis of rotation, wherein a first stop at the base and a second stop at the stator limit the radial and axial compensating movements.
The present invention resides in that the stops at the base and at the stator of the angle measuring system limit the radial and axial movements of the stator in such a way that the coupling between the stator and the base cannot be damaged. Here, the stops in the axial and radial directions are constituted by screws, by which the coupling is fastened on the one end on protruding strips of the base, and which, at the other end, project into bores of a matching size in the stator. The stops in a further radial direction are constituted by the protruding strips of the base itself. In this way stops are obtained for the radial and axial movements of the stator with respect to the base without using additional components.
Further advantages, as well as details, of the present invention ensue from the following description of a preferred embodiment, making reference to the drawings.